What I've personally seen is that the smaller the company the more experienced people you'll have, because they need more independent people and have less time/

What I've personally seen is that the smaller the company the more experienced people you'll have, because they need more independent people and have less time/resources to mentor juniors. So the proportion for a large majority of startups is not similar to what this document shows, which is centered to bigger (1000+ engineers) companies.